AU: Lower HTTP timeout on official builds.
AU: Lower HTTP timeout on official builds.

We grew the timeout from 90s to 3 min a while back to give developers
more time to let the dev server build images. Unfortunately, this
means official builds take longer to time out when they have a bad
HTTP connection. This CL restores the 90s timeout on official builds.

BUG=chromium-os:13793
TEST=on device testing

Change-Id: Ia7a6474331770b3db3425147921d24077452c097

Review URL: http://codereview.chromium.org/6804001

marineam/update_engine,mjg59/update_engine,mjg59/update_engine,marineam/update_engine,marineam/update_engine,marineam/update_engine,endocode/update_engine,mjg59/update_engine,endocode/update_engine,endocode/update_engine